The high price and shortage of natural gas have stimulated the interest of many industrial operations to convert to coal as a fuel. Much of the coal and oil contains a significant amount of sulfur dioxide which must be eliminated to avoid air pollution. There are a number of pollution control techniques that attempt to eliminate sulfur dioxide. These techniques usually require disposing of sulfur dioxide, or some other compound to which it is converted, as a waste material. A typical method involves passing sulfur dioxide containing gas through water. This produces sulfur dioxide which is difficult to dispose of. It is becoming increasingly difficult and expensive to dispose of waste materials without pollution or some type of damage to the environment. In addition, a valuable resource is lost by the destruction of these valuable sulfur containing compounds.
Applicant has discovered a process for converting sulfur dioxide in flue gases into commercially useable aluminum sulfate. The process also produces sodium sulfite which can be readily oxidized to sodium sulfate. This conversion process can be conducted at the fuel burning facility which greatly reduces the cost of pollution control. This process is especially attractive because many industrial operations use aluminum sulfate and/or sodium sulfite or sodium sulfate. Applicant's process can be operated to remove sufficient sulfur dioxide from the effluent flue gas to comply with the most rigid pollution control standards. Contrary to present preferences, it is frequently desirable to utilize coal or oil with a high sulfur content. According to the present invention, sodium aluminate (Na.sub.2 Al.sub.2 O.sub.4) in an aqueous solution or suspension is reacted with dilute sulfur dioxide in a gaseous or aqueous media. This reaction can be conducted in a conventional wet scrubber for industrial flue gases. The reaction product is a soluble sodium sulfite (Na.sub.2 SO.sub.3) and a precipitate containing an aluminum hydroxy sulfite. The precipitate can be separated from the soluble sodium sulfite by conventional means such as filtration. The precipitate can then be oxidized to aluminum sulfate. The sodium sulfite can be oxidized to sodium sulfate.